1. Field of the Invention
The present invention relates to an improved power unit for a sitting-type vehicle having an output shaft connected to driving wheels and projecting in a longitudinal direction of the vehicle body from a casing for an engine mounted in the longitudinal direction of the vehicle body.
2. Description of Background Art
There have already been known various power unit devices as disclosed in, for example, Japanese Patent Application Laid-open No. Hei. 2-112622.
When a crank shaft and an output shaft are provided in parallel in the longitudinal direction of a vehicle body as described above, a power transmission provided between them can be composed of only flat gears. Front and rear driving axles mounted to front and rear wheels can be linked with an output shaft directly. The resulting power unit can be made to be simple in structure with a high rate of transmission efficiency together with many other advantages.
When electric devices, including a generator, are fitted to the inner surface of a front cover or a rear cover connected to an opening provided at either a front or rear section of a casing for an engine in a power unit of the type described above, the maintenance cannot be performed unless the cover is detached from the casing. Such a front cover or rear cover generally includes an output shaft passing therethrough. However, detaching the output shaft requires a driving axle extending from the output shaft to a front or rear wheel to be detached, making the required work extremely troublesome.